Add CheckableResult to standardize checks for deserialized responses

mirai-core-utils/src/commonMain/kotlin/CheckableResult.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2019-2021 Mamoe Technologies and contributors.
+ *
+ * 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ * Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ *
+ * https://github.com/mamoe/mirai/blob/dev/LICENSE
+ */
+
+package net.mamoe.mirai.utils
+
+import kotlinx.serialization.Serializable
+import net.mamoe.mirai.utils.Either.Companion.fold
+import kotlin.reflect.KType
+
+@Suppress("PropertyName")
+public interface CheckableResponse {
+    public val _errorCode: Int
+    public val _errorMessage: String?
+}
+
+@Serializable
+public abstract class CheckableResponseA : CheckableResponse {
+    public abstract val errorCode: Int
+    public abstract val errorMessage: String?
+
+    final override val _errorCode: Int get() = errorCode
+    final override val _errorMessage: String? get() = errorMessage
+}
+
+public class DeserializationFailure(
+    structType: KType,
+    public val json: String,
+    public val exception: Throwable
+) : CheckableResponseA() {
+    override val errorCode: Int get() = -1
+    override val errorMessage: String = "Failed to deserialize '$json' into $structType"
+    public fun createException(): Exception {
+        return IllegalStateException("Error code: $_errorCode, Error message: $_errorMessage", exception)
+    }
+}
+
+public fun <T : CheckableResponse> T.checked(): T {
+    check(_errorCode == 0) { "Error code: $_errorCode, Error message: $_errorMessage" }
+    return this
+}
+
+public fun DeserializationFailure.checked(): Nothing = throw this.createException()
+
+public inline fun <reified T : CheckableResponse> Either<DeserializationFailure, T>.checked(): T {
+    return this.fold(onLeft = { it.checked() }, onRight = { it.checked() })
+}
+
+public inline fun <reified T> Either<DeserializationFailure, T>.checked(): T {
+    return this.fold(onLeft = { it.checked() }, onRight = { it })
+}